1. Field of the Invention
The invention relates to a percussion hammer and/or hammer drill, having a hammer casing which surrounds a percussion mechanism together with drive and holder for a percussion tool and is surrounded, at a distance, by an outer shell which, at selected coupling points, is elastically connected to the hammer casing and at whose end which is remote from the tool in the direction of impact thereof there is a handle.
A tool of this nature is known from DE 40 00 861 C2. In this tool, the vibrations acting on the hand or arm of the person guiding the tool are only reduced to an insufficient extent. Moreover, the spring or damping action has not yet been made sufficiently adaptable to different operating conditions in the prior art.
2. Description of the Related Art
In the design which is known from DE 40 00 861 C2--in the arrangement which is known for tools of this nature--a transmission casing and a motor casing which is connected to the transmission casing follow one after the other in the direction of impact of the tool, starting from the driven tool. These two elements are referred to above for short as the hammer casing. The vibrations which are emitted from this hammer casing are damped with respect to the handle located on the outer shell at the end which is remote from the tool by means of the elastic support between the hammer casing and the outer shell.
To provide reliable guidance for such tools, it is known, and highly advantageous, if a second handle is arranged as close as possible to the percussion tool which projects out of the transmission casing, in order for it to be possible to hold the tool with both hands and to obtain a guide length which is as long as possible.
In the tool which is known from DE 40 00 861 C2, the outer shell does not surround the entire hammer casing, but rather only the section which is formed by the motor casing. This document does not show a second handle. If it were desired to provide such a second handle, it would have to be connected to the transmission casing, and consequently all the vibrations which, as a result of the hammer casing being separate from the outer shell surrounding the motor casing only reach the first handle in damped form, would be transmitted to this second handle without any damping. Not only is this unpleasant when handling the tool, it also impairs reliable guidance of the tool.
DE 34 05 922 A1 has disclosed a handheld power tool in which a hammer casing, which has a handle, surrounds a tool drive, a percussion mechanism and a holder for a percussion tool. The percussion mechanism is secured in the hammer casing via damping elements, while the drive, which is formed by an electric motor, is rigidly connected to the hammer casing. The vibrations which are produced when the electric motor is operating are therefore transmitted to the handle without any damping.